Movable antenna and inspection apparatus

ABSTRACT

According to one embodiment, a movable antenna includes a holder, an antenna radiator element attached to the holder, a first feed element that is attached to the holder and electromagnetically coupled to the antenna radiator element, a base plate in a facing arrangement with the holder, a second feed element on the base plate and configured to face and overlap at least a portion of the first feed element, and a mechanism that moves the holder in a longitudinal direction of the second feed element while maintaining an interval between the first and second feed element permitting energy to be transferred between the first and second feed elements.

CROSS-REFERENCE TO RELATED APPLICATION

This application is based upon and claims the benefit of priority fromJapanese Patent Application No. 2016-146289, filed Jul. 26, 2016, theentire contents of which are incorporated herein by reference.

FIELD

Embodiments described herein relate generally to a movable antenna usedin a radio frequency identification (RFID) reader-writer and aninspection apparatus.

BACKGROUND

In the related art, there is an inspection apparatus that scans articlesone by one with a scanner so as to read a code symbol attached to eacharticle. The inspection apparatus performs an inspection based onarticle information associated with the code symbol. However, in thisinspection apparatus of the related art, since an operator is requiredto scan the articles one by one with the scanner, the operator has tofind a code symbol for each article being scanned and also match thecode symbol with an intended reading direction of the scanner each time.Such a process can be a heavy burden for an inexperienced operator.Likewise, as the number of articles to be inspected increases, theburden on the operator also undesirably increases further.

There is an inspection apparatus that reads information from an RFID tagattached to each article being inspected and performs the inspectionbased on the article information associated with the RFID tag. Forexample, an apparatus that reads tag information from several itemsincluded with a case placed on the upper surface of a counter in which aflat antenna has been embedded.

Such an apparatus is provided with an RFID reader-writer and one or moreantennas, and the RFID reader-writer can read information of RFID tagson the articles in the case via the antenna(s). If a simple flat antennais installed as the antenna, there will be a space/zone at a so-called anull point at which tags will be difficult to read. Therefore, a phasedarray antenna that changes beam direction by controlling the phase of acurrent fed to the plurality of antennas in the phased array and methodsof moving the antenna have been proposed.

However, if a phased array antenna is used in the inspection apparatus,a null point may still occur between array antennas, so that remainsdifficult to read RFID tags at all points within the inspectionapparatus. Furthermore, if the antenna is to be moved, a coaxial cableconnected to the antenna repeatedly bends, such that there is a problemin durability of the cable.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a block diagram of an inspection apparatus according to anembodiment.

FIG. 2 is an external perspective view of a reading device incorporatedin an inspection apparatus.

FIG. 3 is a schematic cross-sectional view of the reading device.

FIG. 4 is a perspective view illustrating a movable antenna according toa first embodiment.

FIG. 5 is a cross-sectional view of the movable antenna.

FIG. 6 is a cross-sectional view illustrating a modified example of themovable antenna.

FIG. 7 is a perspective view illustrating a movable antenna according toa second embodiment.

FIG. 8 is a perspective view illustrating a planar antenna provided inthe movable antenna.

FIG. 9 is a cross-sectional view illustrating a movable antennaaccording to a third embodiment.

DETAILED DESCRIPTION

According to one embodiment, a movable antenna includes a holder, anantenna radiator element attached to the holder, a first feed elementthat is attached to the holder and electromagnetically coupled to theantenna radiator element, a base plate in a facing arrangement with theholder, a second feed element on the base plate and configured to faceand overlap at least a portion of the first feed element, and amechanism that moves the holder in a longitudinal direction of thesecond feed element while maintaining an interval between the first andsecond feed element permitting energy to be transferred between thefirst and second feed elements.

Hereinafter, embodiments will be described with reference to thedrawings.

First Embodiment

FIG. 1 is a block diagram of the configuration of an inspectionapparatus 1 according to a first embodiment. The inspection apparatus 1is installed and used in, for example, a distribution warehouse. Theinspection apparatus 1 includes a controller 10, a reading device 2, adisplay 3, and a memory 4.

The controller 10 controls a moving mechanism 27 for moving a movableantenna 20 of the reading device 2 and a reader-writer 5 connected tothe movable antenna 20. The controller 10 functions as a data processingunit for executing various processes/functions based on information thatis read from a wireless tag (not specifically illustrated) that has beenattached to the article. The wireless tag is, for example, a radiofrequency identification (RFID) tag, in particular, an RFID tagoperating in a UHF band.

FIG. 2 is a perspective view of the reading device 2 incorporated in theinspection apparatus 1. The display 3 is attached to an upper wall of anenclosure 11 (also referred to as an outer casing) of the reading device2. The display 3 is provided with a touch panel 3 a. As the display 3,for example, a liquid crystal display is used.

The enclosure 11 has an opening and closing cover (e.g., a door or alid) 12 which covers an opening 11 a, which is an entrance through whicha case C (see FIG. 3), can be placed into the enclosure 11. The case Cmay include a plurality of articles stored therein. FIG. 2 illustratesthe reading device 2 with the cover 12 in the open state. FIG. 3 is aschematic cross-sectional view of the enclosure 11 with cover 12 closed.

The reading device 2 is incorporated in the inspection apparatus 1 andoutputs (transmits) various information read from the RFID tag to thecontroller 10. In this manner, the reading device 2 is integrated withthe inspection apparatus 1.

The controller 10 executes data processing relating to registration andmanagement of the article according to the information read from theRFID tag attached to the article in the reading device 2.

The RFID tag (not specifically illustrated) stores an article code orthe like for identifying the article to which the tag has been attached.

Thereafter, the reading device 2 will be described.

The enclosure 11 of the reading device 2 is configured in asubstantially box shape. The enclosure 11 has a shape that is long inthe depth direction relative to the lateral width dimension. In theenclosure 11, a reading chamber (storage chamber) 13 having a sizecapable of storing the case C therein is formed.

Outer walls (outer surfaces) of the enclosure 11 and the opening andclosing cover 12 are formed of a radio wave reflecting material such asa metal plate or a molding material, or a radio wave absorbing material.There is no particular limitation on inner walls (inner surfaces) of theenclosure 11 and the opening and closing cover 12. However, the innerwalls may be covered with the radio wave reflecting material or a radiowave absorbing material.

The cover 12 can be opened and closed on a hinge mechanism 111 providedon the side surface portion of the enclosure 11. By placing the cover 12in the open state, an operator can place the case C (in which an articlehas been placed) in of the reading chamber 13 or remove the case C fromthe reading chamber 13.

In the reading chamber 13, the case C is placed on a table 14. The table14 comprises an insulative (radio wave permeable) plate-like materialsuch as wooden or glass, and is supported with a predetermined gap fromthe enclosure 11.

In the reading chamber 13, the movable antenna 20 is provided as an RFIDantenna unit to be used for reading and writing information from/to theRFID tag. The movable antenna 20 is provided with a moving mechanism 27(refer to FIGS. 4 and 5) capable of reciprocating the radiating element21 and a holder 26 holding the radiating element 21 (e.g., a planarantenna), for example, in a horizontal direction parallel to the depthof the reading chamber 13.

The movable antenna 20 is connected to an antenna port of thereader-writer 5 via a coaxial cable connected to a coaxial connector 24or the like. The reader-writer 5 is preferably installed at a positionwhich does not hinder the reading and writing of the RFID tag.Specifically, the reader-writer 5 may be disposed in the enclosure 11but outside the reading chamber 13. The reader-writer 5 may be providedin an empty space, such as a gap between the table 14 and the bottomsurface of the enclosure 11, within the reading chamber 13. In thiscase, the reader-writer 5 further may be covered with a protectivematerial, such as a radio wave absorbing material, to eliminate orreduce the influence of the radio waves on the reader-writer 5 andlikewise the influence on the radio wave environment on the outside ofreading chamber 13 that might be caused by the reader-writer 5.

The moving mechanism 27 is controlled by the controller 10. The movableantenna 20 moves the position of the radiating element 21 with themoving mechanism 27 during the reading of the information from the RFIDtag. That is, the movable antenna 20 starts reading the information fromthe RFID tag and starts the movement of the radiating element 21, andthen stops the movement if the reading is completed.

Inside the reading chamber 13, radio waves radiated from the radiatingelement 21 and radio waves reflected at the enclosure 11 and the likeare combined may form an interference pattern in the reading chamber 13.Communication is performed with the RFID tag(s) within the readingchamber 13, that is, the RFID tag attached to each article contained inthe case C by the combined waves (the directly emitted waves and thereflected waves).

Since the radio waves inside the reading chamber 13 constantly changesby the movement of the radiating element 21 during the reading, a nullpoint, at which the information of the RFID tag(s) cannot be read, canbe reduced or eliminated. Therefore, even if there are several RFID tagsthat are oriented in various directions on the articles included in thecase C, such that, for example, the articles are stacked in anoverlapped manner in the case C, the RFID tags attached to the differentarticles in the case C can still be efficiently, reliably and stablyread.

Thereafter, the detailed configuration of the movable antenna 20 in thefirst embodiment will be described.

FIG. 4 is a perspective view illustrating the movable antenna 20according to the first embodiment, and FIG. 5 is a cross-sectional viewof the movable antenna 20.

The movable antenna 20 includes a rectangular plate-like holder 26, anda rectangular base plate 25. A length of one direction of the base plate25 is equal to one side of the holder 26 and a length of the otherdirection of the base plate 25 is sufficiently longer than the holder26. The holder 26 is held by the moving mechanism 27 in parallel abovethe base plate 25 with a certain interval therebetween. The holder 26 isreciprocally movable along a direction above the base plate 25 whilemaintaining a constant interval with the moving mechanism 27.

The holder 26 holds the radiating element 21 on the upper surfacethereof and holds a first feed element 22 on the lower surface thereof.That is, the radiating element 21 and the first feed element 22 aredisposed in parallel with the holder 26 interposed therebetween, and areattached to the holder 26 so as to be movable in a direction parallel toa length (horizontal direction) of the base plate 25 by the movingmechanism 27.

The moving mechanism 27 includes, for example, a stepping motor, astepping motor driving circuit, a gear, and the like, and the movementdirection and the movement speed thereof are controlled by an externaldevice (e.g., controller 10 or reader-writer 5). The moving mechanism 27is not particularly limited provided the mechanism 27 can move theholder 27 as described.

A second feed element 23 is disposed along the moving direction of theholder 26 at the center of the upper surface of the base plate 25. Thesecond feed element 23 is fixed to the base plate 25 via a holder 28 soas to keep a fixed interval from the base plate 25 and is connected tothe coaxial connector 24 provided at the end portion of the base plate25. The second feed element 23 is disposed up to a range where theradiating element 21 and the first feed element 22 are to be movedintegrally with the holding member 26 from the end portion of the baseplate 25.

The first feed element 22 and the second feed element 23 are providedwith a minute (small) interval. The interval therebetween is smallenough to permit feeding of an electromagnetic signal by anelectromagnetic coupling feeding method between these two feed elements(22 and 23). Thus, these two feed elements (22 and 23) are brought closeto each other. The radiating element 21 and the first feed element 22,which are provided on the holder 26, are reciprocated by the movingmechanism 27 while the minute interval between the first feed element 22and the second feed element 23 is maintained.

The first feed element 22 and the radiating element 21 fixed to theholder 26 can move while partially overlapping the second feed element23 along the longitudinal direction of the second feed element 23.Therefore, while being moved, the first feed element 22 is fed from thesecond feed element 23 using the electromagnetic coupling feedingmethod.

The holder 26 and holder 28 include, for example, a resin such asacrylonitrile butadiene styrene (ABS) or a dielectric such as a glassepoxy substrate. However, the material of the holder 26 and the holder28 is not particularly limited. If the glass epoxy substrate is used forthe holder 26, the radiating element 21 and the first feed element 22can be formed by a copper foil pattern disposed on the glass epoxysubstrate, for example.

The radiating element 21 is fed from the first feed element 22 by aproximity coupling feeding method, which electromagnetically couples theradiating element 21 with the first feed element 22 disposed with theholding member 26 and having a dielectric interposed therebetween.

As a method of feeding the radiating element 21, as illustrated in FIG.6, the radiating element 21 may be connected with the first feed element22 by a feed portion 22 b and fed directly.

If the movable antenna 20 according to the first embodiment is appliedto the inspection apparatus 1, it is desirable that the polarizationcharacteristic of the movable antenna 20 is circularly polarized. In thecase C stored within the reading device 2, the articles may be arrangedin various orientations such that the orientations of the RFID tags arerandom. Therefore, the polarization characteristic of the movableantenna 20 is preferably circularly polarized, so that the informationof the RFID tags attached to the articles can be reliably read no matterthe particular orientation of an article within the case C.

In the movable antenna 20 illustrated in FIG. 4, a notch is provided ata pair of diagonal corners of the radiating element 21 so as to functionas a circular polarized antenna. Such a notch is generally called adegenerate separation element or a perturbation element. It is possibleto use a configuration in which not only the notch is in the squareradiating element 21 as illustrated in FIG. 4, but also a notch is in acircular radiating element.

In this manner, in the movable antenna 20 according to the firstembodiment, the radiating element 21 and the first feed element 22 canmove integrally with the holder 26 interposed therebetween, while theminute interval is maintained between the first feed element 22 and thesecond feed element 23, and power can be fed by the electromagneticcoupling feeding method. That is, since the radiating element 21 has noparts that bend while the antenna moves, unlike a coaxial cableconnecting to a fixed feed element, the durability of the movableantenna 20 can be improved.

Second Embodiment

Thereafter, a second embodiment will be described. In the secondembodiment, instead of the movable antenna 20 as in the firstembodiment, a movable antenna 40 (illustrated in FIGS. 7 and 8) isprovided in the reading device 2.

FIG. 7 is a perspective view illustrating the movable antenna 40according to the second embodiment, and FIG. 8 is a perspective viewillustrating a planar antenna 30 provided in the movable antenna 40.

Substantially similar aspect of movable antenna 40 (illustrated in FIG.7) are denoted by the same reference numerals as those of the movableantenna 20 (illustrated in FIGS. 4 and 5), and a detailed description ofthese aspects will be omitted.

The movable antenna 40 has a planar antenna 30 instead of the radiatingelement 21 and the first feed element 22 (each integrated with theholding member 26) of the movable antenna 20 (illustrated in FIG. 4).

In the planar antenna 30, as illustrated in FIG. 8, a radiating element21 and a first feed element 32 are integrated on the front and backsurfaces of a dielectric substrate 33, respectively. Inside thedielectric substrate 33, a base plate 35 is formed as an inner layer.The base plate 35 is provided with a slot 34 in a direction orthogonalto the first feed element 32 and is disposed in the vicinity immediatelybelow the radiating element 21. This configuration is the same as amicro strip antenna of a slot coupled feeding method. The radiatingelement 21 is fed by being electromagnetically coupled to the first feedelement 32 via the slot 34.

The planar antenna 30 can be moved in parallel (along a horizontaldirection) to the base plate 25 by a moving mechanism 27, similarly tothe first embodiment. The moving mechanism 27 can hold the planarantenna 30 and cause the planar antenna 30 to reciprocate along thelongitudinal direction of the second feed element 23.

The first feed element 32 and the second feed element 23 are formed onthe back surface of the dielectric substrate 33 and are provided with aninterval therebetween that is capable of feeding by the electromagneticcoupling feeding method, and are thus brought close to each other. Theplanar antenna 30 is reciprocated by the moving mechanism 27 while theinterval between the first feed element 32 and the second feed element23 is maintained.

The planar antenna 30 can move while partially overlapping with thesecond feed element 23 in a direction parallel to a length of the secondfeed element 23. Therefore, while moving, the first feed element 32provided in the planar antenna 30 is fed from the second feed element 23by the electromagnetic coupling feeding method.

In this manner, in the movable antenna 40 according to the secondembodiment, the planar antenna 30 can move, while the interval ismaintained between the first feed element 32 of the planar antenna 30and the second feed element 23 and power can be fed by theelectromagnetic coupling feeding method. Therefore, the durability ofthe movable antenna 40 can be improved, similarly to the firstembodiment.

Third Embodiment

Thereafter, a third embodiment will be described. In the thirdembodiment, instead of the movable antenna 20 as in the firstembodiment, a movable antenna 50 illustrated in FIG. 9 is provided inthe reading device 2.

FIG. 9 is a cross-sectional view illustrating the movable antenna 50according to the third embodiment.

Aspects of movable antenna 50 illustrated in FIG. 9 that are denoted bythe same reference numeral as that of the movable antenna 20 illustratedin FIGS. 4 and 5, are substantially the same as the aspects previouslyexplained and a detailed description thereof will be omitted.

In the movable antenna 50 according to the third embodiment, asillustrated in FIG. 9, a minute interval is between the first feedelement 22 and the second feed element 23, and the first feed element 22and the second feed element 23 are connected by a contact point 29. Thecontact point 29 is fixed to, for example, the first feed element 22,and with the movement of the radiating element 21 and the first feedelement 22, the contacting position of the contact point 29 with thesecond feed element 23 moves.

The radiating element 21 and the first feed element 22 are reciprocatedby the moving mechanism 27 while the first feed element 22 and thesecond feed element 23 are connected by the contact point 29. Therefore,the first feed element 22 is fed from the second feed element 23 via thecontact point 29 while moving.

As a method of feeding to the radiating element 21, similarly to thefirst embodiment, the proximity coupling feeding method thatelectromagnetically couples with the first feed element 22 may be used.Further, as illustrated in FIG. 6, a direct feeding method in which thefirst feed element 22 and the radiating element 21 are connected by afeed cable 22 b may be used.

It is also possible to connect the first feed element 32 and the secondfeed element 23 described above in the second embodiment by using thecontact point 29. In this case, the contact point 29 is fixed to, forexample, the first feed element 32, and with movement of the movableantenna 40, the contact position of the contact point 29 in contact withthe second feed element 23 moves.

In this manner, in the movable antenna 50 according to the thirdembodiment, the first feed element 22 and the second feed element 23 areconnected by the contact point 29 and power can thus be fed so that theradiating element 21 and the first feed element 22 (which are integratedwith the holding member 26 interposed therebetween) can be moved. Thatis, since the radiating element 21 has no parts that bend while theantenna moves, unlike a coaxial cable connecting to a fixed feedelement, the durability of the movable antenna 50 can be improved.

In each of the example embodiments described above, the reading device 2is provided with one movable antenna. However, a plurality of movableantennas may be provided. A movable antenna may be provided at locationsother than at the bottom surface of the enclosure 11, as illustrated inFIG. 3, but also maybe disposed on the side surface or the rear surfaceof the enclosure 11 or on the cover 12.

In each of the example embodiments described above, the inspectionapparatus 1 is operated by an operator as described for warehouseinventory management. However, these embodiments can also be applied toan inspection apparatus (e.g., cash register) operated by a clerk (e.g.,cashier).

The movable antennas 20, 40, and 50 can be applied not only to aninspection apparatus 1 but also to other apparatuses that move aradiating element (e.g., antenna) for reading information from an RFIDtag.

While certain embodiments have been described, these embodiments havebeen presented by way of example only, and are not intended to limit thescope of the inventions. Indeed, the novel embodiments described hereinmay be embodied in a variety of other forms; furthermore, variousomissions, substitutions and changes in the form of the embodimentsdescribed herein may be made without departing from the spirit of theinventions. The accompanying claims and their equivalents are intendedto cover such forms or modifications as would fall within the scope andspirit of the inventions.

What is claimed is:
 1. A movable antenna, comprising: a holder; anantenna radiator element attached to the holder; a first feed elementthat is attached to the holder and electromagnetically coupled to theantenna radiator element; a base plate in a facing arrangement with theholder; a second feed element on the base plate and configured to faceand overlap at least a portion of the first feed element; and amechanism that moves the holder in a longitudinal direction of thesecond feed element while maintaining an interval between the first andsecond feed element permitting energy to be transferred between thefirst and second feed elements.
 2. The movable antenna according toclaim 1, wherein the radiating element is a planar antenna.
 3. Themovable antenna according to claim 1, wherein the antenna radiatorelement is a portion of a phased array antenna.
 4. The movable antennaaccording to claim 1, wherein the first feed element iselectromagnetically coupled to the second feed element across theinterval.
 5. The movable antenna according to claim 1, furthercomprising a contact portion attached to the first feed element andspanning the interval between the first and second elements to contactthe second feed element, wherein energy is transferred between the firstand second feed elements via conduction through the contact portion. 6.The movable antenna according to claim 1, further comprising a coaxialconnector disposed on the base plate and electrically connected to thesecond feed element.
 7. The movable antenna according to claim 1,wherein the antenna radiator element is disposed on an upper surface ofthe holder, the first feed element is disposed on a lower surface of theholder, and the holder is a dielectric material.
 8. The moveable antennaaccording to claim 7, wherein the antenna radiator element and the firstfeed element comprise metal foil patterns.
 9. The moveable antennaaccording to claim 7, wherein the antenna radiator element and the firstfeed element are electromagnetically coupled to each other across athickness of the holder.
 10. The moveable antenna according to claim 1,further comprising an electrical connection portion from the first feedelement to the antenna radiator element through the holder.
 11. Anelectronic tag reading apparatus, comprising: a casing including achamber into which an electronic tag can be placed for reading; amoveable antenna placed in proximity to the chamber, the moveableantenna comprising: a holder; an antenna radiator element attached tothe holder; a first feed element that is attached to the holder andelectromagnetically coupled to the antenna radiator element; a baseplate in a facing arrangement with the holder; a second feed element onthe base plate and configured to face and overlap at least a portion ofthe first feed element; and a mechanism that moves the holder in alongitudinal direction of the second feed element while maintaining aninterval between the first and second feed element permitting energy tobe transferred between the first and second feed elements.
 12. Theelectronic tag reading apparatus according to claim 11, furthercomprising: a controller configured to cause the mechanism to move theholder in the longitudinal direction of the second feed element during atag reading process.
 13. The electronic tag reading apparatus accordingto claim 11, further comprising: a plate in the chamber and disposedbetween the moveable antenna and the electronic tag, the plate beingcomprised of a material that is permeable to a signal radiated by themoveable antenna.
 14. The electronic tag reading apparatus according toclaim 11, further comprising: a tag reader-writer connected to themoveable antenna and configured to supply a signal to the moveableantenna.
 15. The electronic tag reading apparatus according to claim 11,wherein the electronic tag is a radio frequency identification (RFID)tag operating in an ultrahigh frequency (UHF) band.
 16. The electronictag reading apparatus according to claim 11, wherein the antennaradiator element is one of a planar antenna and a portion of a phasedarray antenna.
 17. The electronic tag reading apparatus according toclaim 11, wherein the first feed element is electromagnetically coupledto the second feed element across the interval.
 18. The electronic tagreading apparatus according to claim 11, further comprising a contactportion attached to the first feed element and spanning the intervalbetween the first and second elements to contact the second feedelement, wherein energy is transferred between the first and second feedelements via conduction through the contact portion.
 19. A RFID tagreading apparatus, comprising: a casing including a chamber into whichan item to which an RFID tag has been attached can be placed forreading; a reader-writer for generating signals for reading the RFIDtag; a moveable antenna placed in proximity to the chamber, the moveableantenna comprising: a holder; an antenna radiator element attached tothe holder; a first feed element that is attached to the holder andelectromagnetically coupled to the antenna radiator element; a baseplate in a facing arrangement with the holder; a second feed element onthe base plate and configured to face and overlap at least a portion ofthe first feed element; a mechanism that moves the holder in alongitudinal direction of the second feed element while maintaining aninterval between the first and second feed element permitting energy tobe transferred between the first and second feed elements; and a coaxialconnector disposed on the base plate and electrically connected to thesecond feed element, wherein the reader-writer is connected to thecoaxial connector via coaxial cable; and a controller configured toreciprocate the moveable antenna along the longitudinal direction of thesecond feed element during a reading process.
 20. The RFID tag readingapparatus according to claim 19, wherein the antenna radiator element isone of a planar antenna and a portion of a phased array antenna.